Scientists are developing a new method of providing people with instant protection against flu.

Researchers at the University of Warwick said they have created a "protecting virus" which slows the rate of infection to such an extent that the flu virus effectively becomes its own vaccine.

Experts said existing vaccination methods stimulated the body's immune system, so that white blood cells produced antibodies that attached to the surface of the virus and started the process of killing it.

This method works for diseases including smallpox, polio and measles but is less effective with influenza, as the coat of the flu virus is continually changing.

It also means that vaccination against one strain of flu is totally ineffective against another.

Preliminary tests are said to show that this new method could offer protection against the full range of influenza A infections.

A University of Warwick press release stated: "One could give the 'protecting virus' as a preventive measure without the need to tailor it to a particular flu strain or mutation.

"This has obvious benefits when dealing with the sudden outbreak of a major epidemic, as one would not need to know the exact make up of the new strain before deploying the protecting virus, making it much more useful than vaccines, which are effective only against particular existing strains of virus."